1. Field of the Invention
The present invention relates to a fuel injection device of a diesel engine, more particularly, to a fuel injection device adapted to a diesel engine having an intake air throttling valve in an intake side of the engine.
2. Description of the Prior Art
In fuel injection devices of diesel engines, one known method for stopping the fuel supply comprises cutting off the fuel when the engine has stopped by operating a key switch to actuate a solenoid valve and shut a fuel passage. Another known method comprises reducing the fuel injection quantity to zero by the centrifugal force of a flyweight when the engine exceeds a predetermined rotational speed during no-load running. These methods thus help prevent engine damage.
Diesel engines involve higher compressive forces compared with gasoline engines and, therefore, have greater vibration and noise. Attempts have been made to reduce the vibration and noise of diesel engines by throttling the intake air and reducing the compressive force. This, however, results in poorer combustion and, thus, reduced output and greater harmful exhaust gas. Because of this, it has been proposed to throttle the intake air only during engine idling when there would be little effect on the output. Throttling of the intake air, however, is not easy during engine braking since the engine speed undergoes a large change. There has yet to be proposed an effective method which prevents increased harmful exhaust gas due to poorer combustion and which reduces vibration and noise under such an engine operating condition.